Logic Pro

An MCP server that lets an AI assistant operate Apple Logic Pro — transport, mixing, a full Mackie Control surface, playhead positioning, and MIDI region read/write.

Why it exists

Logic is the least scriptable major DAW: no AppleScript API and no plugin SDK that reaches project data. This server stitches together the macOS channels that do work — and deliberately favours the ones that don't force Logic to the foreground:

• Mackie Control (MCU) over MIDI for transport, the mixer, and the control surface — channels addressed by number, like real hardware.
• Accessibility (AX) value reads/sets for playhead position (focus-independent).
• SMF round-trip + IAC streaming for reading and writing region note data.

Architecture

Claude ⇄ MCP server (TypeScript) ⇄ JSON-RPC over stdio ⇄ Python worker
        src/index.ts  src/bridge.ts                       python/worker.py
                                                            ├── logic/mcu.py          Mackie Control surface (persistent)
                                                            ├── logic/mcu_protocol.py MCU byte map + codecs
                                                            ├── logic/midiport.py     MMC + IAC streaming (rtmidi)
                                                            ├── logic/write_region.py playhead + record-to-track
                                                            ├── logic/export_region.py region export (AX)
                                                            ├── logic/smf.py          SMF read/write (mido)
                                                            ├── logic/axui.py         Accessibility helpers
                                                            └── logic/keys.py         CGEvent keys (fallback)

TypeScript owns only the MCP protocol. Python owns all MIDI and macOS-native work, and is testable standalone via python/cli.py and python/mcudev.py.

Supported operations

• Transport — play / stop / record over the MCU surface (background, no foreground; falls back to MMC then key commands).
• Tracks — list all channels (numbered, scanned across banks) with live state: arm, mute, solo, select, fader, pan, meter.
• Track control — arm / mute / solo / select any channel by number.
• Mixing — set volume (precise), pan, or center-pan, per channel or master.
• Surface — read full control-surface state (faders, V-pots, meters, timecode, lit buttons) and press any Mackie button with modifiers.
• Playhead — read position and go-to-bar via AX (focus-independent).
• Cycle — read or set the loop region (start/end bar) and toggle cycle on/off via AX (focus-independent).
• MIDI content — read the selected region or whole timeline as note data; record notes onto a track at a bar (IAC streaming); write notes to a .mid.

Installation

npm install
python3 -m venv .venv && .venv/bin/pip install -r python/requirements.txt
npm run build

macOS setup:

1. Grant Accessibility permission to the worker's host process (System Settings ▸ Privacy & Security ▸ Accessibility).
2. Create two IAC Driver buses in Audio MIDI Setup: IAC Driver MCU Cmd and IAC Driver MCU Fb, plus IAC Driver Bus 1 for note streaming.
3. In Logic ▸ Settings ▸ MIDI: enable MMC input ("Listen to MMC Input"), add a Mackie Control surface using MCU Cmd as Input and MCU Fb as Output, and filter both MCU buses out of track inputs.
4. For cycle locator control: show the locators in the Control Bar LCD (right-click the Control Bar ▸ Customize Control Bar and Display ▸ LCD ▸ Custom ▸ check Locators (Bar/Beat)).

Configure your AI harness

The server is a stdio MCP server: run dist/index.js with node, and set LOGIC_MCP_PYTHON to the venv's Python so the worker uses the right interpreter. Use absolute paths everywhere — most harnesses don't run from this directory. (dist/ is gitignored, so run npm run build first.)

The base config block, reused by every harness below:

{
  "command": "/ABSOLUTE/PATH/TO/node",
  "args": ["/ABSOLUTE/PATH/logic-pro-mcp/dist/index.js"],
  "env": { "LOGIC_MCP_PYTHON": "/ABSOLUTE/PATH/logic-pro-mcp/.venv/bin/python" }
}

Find your absolute paths with which node and pwd.

Claude Code — register from the repo root (writes to ~/.claude.json):

npm run build
claude mcp add logic-pro "$(which node)" "$(pwd)/dist/index.js" \
  --env LOGIC_MCP_PYTHON="$(pwd)/.venv/bin/python"

Or drop a .mcp.json in a project root to share it with that project (claude mcp add with --scope project does the same):

{ "mcpServers": { "logic-pro": { <base config block> } } }

Claude Desktop — edit ~/Library/Application Support/Claude/claude_desktop_config.json, add the server under mcpServers, then restart the app:

{ "mcpServers": { "logic-pro": { <base config block> } } }

Other harnesses (Cursor, Cline, custom SDK clients) take the same shape: a stdio server with command, args, and env. Consult the host's MCP docs for where its config file lives.

After registering, confirm the tools load (in Claude Code: /mcp should list logic-pro). If they don't, check the worker can start standalone: .venv/bin/python python/worker.py and send {"id":1,"method":"ping"}.